3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||104.07 g/mol|
|Appearance||Colorless crystalline solid|
|Melting point||257 °C (495 °F; 530 K)|
|3.45 g/kg (in water at 25 °C)|
|Shock sensitivity||> 50 J|
|Friction sensitivity||> 350 N|
|Occupational safety and health (OHS/OSH):|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Nitroguanidine - sometimes abbreviated NGu - is a colorless, crystalline solid that melts at 257 °C and decomposes at 254 °C. Nitroguanidine is an extremely insensitive but powerful high explosive. Wetting it with > 20 wt.-% water effects desensitization from HD 1.1 down to HD 4.1 (flammable solid). Nitroguanidine is used as an energetic material, i.e., propellant or high explosive, precursor for insecticides, and for other purposes.
Nitroguanidine is produced worldwide on a large scale starting with the reaction of dicyandiamide (DCD) with ammonium nitrate to afford the salt guanidinium nitrate, which is then nitrated by treatment with concentrated sulfuric acid at low temperature.
- [C(NH2)3]NO3 → (NH2)2CNNO2 + H2O
Nitroguanidine can also be generated by treatment of urea with ammonium nitrate (via the BMA process). However, owing to problems of reliability and safety, this process has never been commercialized despite its attractive economic features.
Nitroguanidine has been in use since the 1930s as an ingredient in triple-base gun propellants in which it reduces flame temperature, muzzle flash, and erosion of the gun barrel but preserves chamber pressure due to high nitrogen content. Its extreme insensitivity combined with low cost has made it a popular ingredient in insensitive high explosive formulations (e.g AFX-453, AFX-760, IMX-101, AL-IMX-101, IMX-103, etc.).
Nitroguanidine's explosive decomposition is given by the following equation: H4N4CO2 (s) → 2 H2O (g) + 2 N2 (g) + C (s)
Nitroguanidine derivatives are used as insecticides, having a comparable effect to nicotine. Derivatives include clothianidin, dinotefuran, imidacloprid, and thiamethoxam.
The nitrosoylated derivative, nitrosoguanidine, is often used to mutagenize bacterial cells for biochemical studies.
Following several decades of debate, it could be confirmed by NMR spectroscopy, and both x-ray and neutron diffraction that nitroguanidine exclusively exists as the nitroimine tautomer both in solid state and solution.
- ^ United Nations, Transport of Nitroguanidine, wetted, (UN 1336) in flexible IBCs, ST/SC/AC.10/C.3/2006/52, Geneva, 13 April 2006. Accessed at https://www.unece.org/fileadmin/DAM/trans/doc/2006/ac10c3/ST-SG-AC10-C3-2006-52e.pdf
- ^ E.-C. Koch, Insensitive High Explosives: III. Nitroguanidine – Synthesis – Structure – Spectroscopy – Sensitiveness, Propellants Explos. Pyrotech. 2019, 44, 267-292. 
- ^ E.-C. Koch, Insensitive High Explosives: IV. Nitroguanidine - Initiation & detonation, Def. Tech. 2019, 15, 467-487.
- ^ Bulusu, S.; Dudley, R. L.; Autera, J. R. (1987). "Structure of nitroguanidine: nitroamine or nitroimine? New NMR evidence from nitrogen-15 labeled sample and nitrogen-15 spin coupling constants". Magnetic Resonance in Chemistry. 25 (3): 234–238. doi:10.1002/mrc.1260250311. S2CID 97416890.
- ^ Murmann, R. K.; Glaser, Rainer; Barnes, Charles L. (2005). "Structures of nitroso- and nitroguanidine x - ray crystallography and computational analysis". Journal of Chemical Crystallography. 35 (4): 317–325. doi:10.1007/s10870-005-3252-y. S2CID 96090647.
- ^ S. Choi, Refinement of 2-Nitroguanidine by Neutron Powder Diffraction, Acta Crystallogr. B 1981, 37, 1955-1957.